【摘要】：隨著采礦、冶煉、電鍍、電子及燃料生產(chǎn)等行業(yè)的快速發(fā)展,越來越多的鉛鋅等重金屬通過多種途徑進(jìn)入土壤或水體環(huán)境中,對生態(tài)環(huán)境和人類健康造成了嚴(yán)重威脅。近年來,利用耐性微生物治理重金屬污染已成為一個(gè)新型的研究領(lǐng)域。本研究通過從湖南某鉛鋅礦區(qū)的先鋒植物根際土壤中,分離、篩選出一株對鉛鋅耐性較強(qiáng)的菌株,考察了其對鉛、鋅去除能力的主要影響因素,并對其吸附機(jī)理進(jìn)行初步探討,以期為今后重金屬污染微生物修復(fù)的工業(yè)化應(yīng)用提供參考。本論文研究的主要內(nèi)容和結(jié)論如下：(1)從鉛鋅礦區(qū)純化分離出11株菌株,初步篩選得到3株耐性菌,選定其中耐性最高的菌株HA作為本研究的實(shí)驗(yàn)菌株,菌株HA對鉛、鋅離子都有較高耐性的,且其對鉛離子的去除效率高于鋅離子。通過對菌株HA的形態(tài)及DNA測序分析,最終鑒定HA為米曲霉(Aspergillus oryzae)。(2)通過單因素實(shí)驗(yàn)及正交實(shí)驗(yàn)對耐性菌HA吸附鉛鋅離子的環(huán)境條件進(jìn)行了優(yōu)化,得到如下結(jié)論：①在初始鉛、鋅濃度的實(shí)驗(yàn)范圍內(nèi)(100-800 mg/L),HA對鉛、鋅離子的去除率隨著其初始濃度增加而減小,當(dāng)鉛、鋅初始濃度為100 mg/L、pH為5.0時(shí),HA對鉛、鋅離子的去除率均達(dá)到最高,分別為97.8%、54.1%；生長曲線分析表明,25 h后HA的生長進(jìn)入平穩(wěn)期,且對鉛、鋅離子的去除率趨于穩(wěn)定。當(dāng)HA接種量為1 mL時(shí),其對鉛、鋅去除率的增長率達(dá)到最大。②在單因素實(shí)驗(yàn)結(jié)果的基礎(chǔ)上,選擇重金屬離子的初始濃度、pH、接種量、吸附時(shí)間四因素中,較顯著的3個(gè)水平,進(jìn)行正交實(shí)驗(yàn),最終確定HA吸附鉛、鋅離子的最優(yōu)方案都為：初始濃度為100mg/L時(shí),培養(yǎng)基pH為5.5,接種量為菌濃度為0.01 g/mL的菌液1.5 mL,吸附時(shí)間為3 d。(3)通過等溫吸附模型、動(dòng)力學(xué)分析、掃描電鏡、能譜分析、紅外光譜等手段對耐性菌HA吸附鉛和鋅離子的機(jī)理進(jìn)行初步探討,并對HA細(xì)胞吸附鉛、鋅的吸附部位進(jìn)行了初步研究,得到如下結(jié)論：①對菌株HA吸附鉛、鋅離子的吸附等溫模式和吸附動(dòng)力學(xué)進(jìn)行分析,發(fā)現(xiàn)HA對鉛、鋅的吸附過程滿足Langmuir吸附模型,其吸附以單層吸附為主。在動(dòng)態(tài)吸附過程中,HA對Pb2+、Zn2+離子吸附性能與準(zhǔn)二級動(dòng)力學(xué)吸附方程的擬合程度更高,且對Pb2+的吸附效果明顯高于Zn2+。②對HA細(xì)胞吸附鉛、鋅離子的吸附部位進(jìn)行研究,結(jié)果表明耐性菌株HA對Pb2+、Zn2+的生物吸附和累積主要以細(xì)胞壁吸附和細(xì)胞內(nèi)累積為主,其中胞壁吸附量高于胞內(nèi)累積量,說明菌株HA細(xì)胞壁上的某些成分及活性基團(tuán)對Pb2+、Zn2+的結(jié)合能力較強(qiáng)。③掃描電鏡和能譜分析結(jié)果表明在吸附Pb2+、Zn2+后菌株表面有較多含鉛、鋅的沉淀物。IR分析表明：HA細(xì)胞中羥基、烷基、酰胺基、羰基、磷酸基等參與了Pb2+、Zn2+的吸附,使特征峰吸收強(qiáng)度和位置都出現(xiàn)不同程度的變化。
[Abstract]:With the rapid development of mining, smelting, electroplating, electronics and fuel production, more and more heavy metals, such as lead and zinc, enter the soil or water environment through many ways, which pose a serious threat to the ecological environment and human health. In recent years, the treatment of heavy metal pollution by tolerant microorganisms has become a new research field. In this study, a strain with strong tolerance to lead and zinc was isolated from the rhizosphere soil of a pioneer plant in a lead-zinc mining area in Hunan Province. The main factors affecting the removal capacity of lead and zinc were investigated, and the adsorption mechanism was preliminarily discussed. In order to provide reference for the industrial application of heavy metal contaminated microorganism remediation in the future. The main contents and conclusions of this paper are as follows: (1) 11 strains were isolated from lead-zinc mining area, and 3 resistant strains were screened. The most resistant strain HA was selected as the experimental strain in this study. Zinc ion has higher tolerance, and its removal efficiency of lead ion is higher than that of zinc ion. By analyzing the morphology and DNA sequencing of the strain HA, the HA was identified as (Aspergillus oryzae). (2. The environmental conditions for the adsorption of lead and zinc ions by the resistant strain HA were optimized by single factor experiment and orthogonal experiment. In the experimental range of zinc concentration (100-800 mg / L), the removal rate of zinc ion decreased with the increase of the initial concentration of lead and zinc. When the initial concentration of lead and zinc was 100 mg / L ~ (-1) pH 5.0, the removal rate of lead and zinc ions reached the highest, which were 97.8mg / L ~ 54.1, respectively. Growth curve analysis showed that the growth of HA reached a stable stage after 25 h, and the removal rate of lead and zinc ions tended to be stable. When the inoculation amount of HA was 1 mL, the removal rate of lead and zinc reached the maximum of .2. On the basis of the results of single factor experiments, three levels of heavy metal ions were selected as follows: pH value, inoculation amount and adsorption time. The results of orthogonal experiment showed that the best schemes for adsorption of lead and zinc ions by HA were as follows: when the initial concentration was 100 mg / L, the medium pH was 5.5, the inoculation amount was 1.5 mL of bacteria concentration 0.01 g / mL, and the adsorption time was 3 days. (3) the isothermal adsorption model was used. Kinetic analysis, scanning electron microscopy, energy dispersive analysis and infrared spectroscopy were used to study the mechanism of adsorption of lead and zinc ions by HA, and the adsorption sites of lead and zinc on HA cells were also studied. The results showed that the adsorption isotherm and kinetics of lead and zinc ions were analyzed. It was found that the adsorption process of HA for lead and zinc was consistent with Langmuir adsorption model, and monolayer adsorption was the main adsorption process. The adsorption of Pb ~ (2 +) ~ (2 +) and Zn ~ (2 +) on HA was better than that of Zn _ (2) 2 on HA, and the adsorption sites of Pb ~ (2 +) and Zn ~ (2 +) were higher than that of Zn _ (2) 2. The results showed that the biosorption and accumulation of Pb _ 2 ~ (2 +) Zn _ (2) by the tolerant strain HA were mainly cell wall adsorption and intracellular accumulation, in which the cell wall adsorption was higher than the intracellular accumulation. The results showed that the binding ability of some components and active groups on HA cell wall to Pb 2 + Zn 2 was stronger. 3. The results of SEM and EDS showed that there was more lead on the surface of the strain after adsorption of Pb 2 + Zn 2. Ir analysis of zinc precipitates showed that hydroxyl, alkyl, amide, carbonyl and phosphate groups were involved in the adsorption of Pb ~ (2 +) ~ (2 +) Zn _ (2), and the absorption intensity and position of the characteristic peaks were changed in different degrees.
【學(xué)位授予單位】：中南林業(yè)科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X172

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相關(guān)期刊論文 前1條

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本文編號(hào)：2119200